1. Field of the Invention
Embodiments disclosed herein relate to apparatuses and methods used in downhole tools. More specifically, embodiments disclosed herein relate to apparatuses and methods used in actuating downhole tools. More specifically still, embodiments disclosed herein relate to apparatuses and methods used in the actuation of multiple downhole tools during sequenced operations, such as hydraulic fracturing operations.
2. Background Art
This section of this document introduces various information from the art that may be related to or provide context for some aspects of the technique described herein and/or claimed below. It provides background information to facilitate a better understanding of that which is disclosed herein. This is a discussion of “related” art. That such art, is related in no way implies that it is also “prior” art. The related art may or may not be prior art. The discussion in this section is to be read in this light, and not as admissions of prior art.
Prior to producing or in order to further stimulate the production of hydrocarbons from underground reservoir rock formation, a well may be fractured through a process known in the art as hydraulic fracturing, hydrofracing or fracing. Hydraulic fracturing involves the propagation of fractures in formation caused by pumping pressurized fluid from the surface of a well. Examples of fluids that may be used in hydraulic fracturing operations include combinations of water, proppants, and chemical additives in the form of liquids, gels, foams, and gas. Examples of gases that may be injected include compressed nitrogen, carbon dioxide, and air. By hydraulically fracturing a well a greater rate of production of hydrocarbons may be achieved.
As wells may be thousands of feet long, it is often necessary to conduct multiple hydraulic fracturing operations, for example, every several hundred feet, in order to increase the production of hydrocarbons from the well. In order to hydraulically fracture the well at multiple locations, a series of valves may be run downhole and set at specific depths within the well. In conventional downhole valves used in multiple hydraulic fracturing operations, multiple valves are run to specific depths within the well that open within one given stage, for example, with one ball size. The valves have expandable sleeves, such that when a ball is dropped from the surface and pushed downward within the well by pressure from above, a sleeve under a ball seat of the valve opens. After opening, the ball seat expands and the ball is allowed to continue down to the next expandable sleeve.
The process may then repeat itself, so long as the ball remains structurally intact. The ability of this process to be effective is limited by the strength of the ball used, as well as the interference between the ball and the ball seat necessary to withstand the differential pressure during the hydraulic fracturing process. Presently, ball drop systems used in hydraulic fracturing processes are limited to about 23 actuation cycles for a 4.5 inch system and about 28 actuation cycles for a 5.5 inch system. As well are drilled deeper to access deeper hydrocarbon reserves, more hydraulic fracturing stages are required in order to properly hydraulically fracture a well.
Such conventional systems also are not proven to create separate fractures with any reliability. In such systems, pumping fracturing fluids down the well with multiple valves open at once has not improved the number or productivity of the fractures, thereby wasting time, money, and fluids, without seeing a return on investment.